1. Field of the Invention
The present invention relates generally to a locking device for a foldable stroller. More particularly, the present invention relates to a two-stage locking device which is applied in the stroller capable of both folding and unfolding.
2. Description of Related Art
The conventional stroller, baby bed and baby dinner chair etc. are generally constructed of a plurality of tubular elements. Take a stroller for example, which is constructed of a plurality of tubular elements mutually connected to form a main frame in which a seating area of an infant is provided by mounting a clothing pad thereon, and wheels are connected thereon to benefit moving freely. All these baby products have the same design, the tubular elements can be folded and movably shrink together to a smaller size in volume when not in use. That is, the tubular elements are mutually movable toward each other. Of course, these tubular elements can also be fixed while in use by putting a locking mechanism between two tubular elements and released to fold up. Take the U.S. Pat. No. 5,876,057 for example, it disclosed a stroller which is composed of upper support and a set of lower supports pivotally connected with the upper support and having a pair of symmetrically opposed front supports, a pair of symmetrically opposed rear supports each pivotally connected with each of the pair of the front supports and a seat pivotally and respectively connected with the upper support, the front supports and the rear supports. A slot is defined in a periphery of the upper support for movably receiving a post. The post is constrained within the slot and connected with a spring. The upper support and the front support are securely connected together until the protrusion is pulled to disengage from the post. After the protrusion is pulled, the stroller is about to be folded. However, it has a tendency to misactivate the stroller to fold up that using only one step to disengage the protrusion from securely connected status. The unwanted operation may even be made by a baby or an unexpected touch. Danger happens under this condition.
To avoid this kind of dangerous operation, an additional safe lock is important except the aforesaid engaging mechanism. Referring to FIGS. 1A and 1B, it illustrate embodiment of the present in different operation position. The stroller of the present invention comprises a front frame 41, rear frame 42, wheel 43 and handle frame 44. The handle frame 44 is pivotally connected with front frame 41 and has a first safe lock 45 and a second safe lock 46 movably connected thereon. When the stroller is expanded, the first lock 45 and the second lock 46 both engage with the front frame 41. On case of folding the stroller, the first lock 45 is firstly disengaged from the front frame 41, and the second lock 46 is then turned to fully disengage them. This two-stage operation allows the handle frame 44 to move toward the front frame 41, and the stroller is folded. The stroller equipped with two-stage lock disclosed in the present invention will be safer and can securely protect a baby because there are two processes to disengage the frames being folded.